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ubidi.h (91759B)

---

// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
******************************************************************************
*
*   Copyright (C) 1999-2013, International Business Machines
*   Corporation and others.  All Rights Reserved.
*
******************************************************************************
*   file name:  ubidi.h
*   encoding:   UTF-8
*   tab size:   8 (not used)
*   indentation:4
*
*   created on: 1999jul27
*   created by: Markus W. Scherer, updated by Matitiahu Allouche
*/

#ifndef UBIDI_H
#define UBIDI_H

#include "unicode/utypes.h"
#include "unicode/uchar.h"

#if U_SHOW_CPLUSPLUS_API
#include "unicode/localpointer.h"
#endif   // U_SHOW_CPLUSPLUS_API

/**
*\file
* \brief C API: Bidi algorithm
*
* <h2>Bidi algorithm for ICU</h2>
*
* This is an implementation of the Unicode Bidirectional Algorithm.
* The algorithm is defined in the
* <a href="http://www.unicode.org/unicode/reports/tr9/">Unicode Standard Annex #9</a>.<p>
*
* Note: Libraries that perform a bidirectional algorithm and
* reorder strings accordingly are sometimes called "Storage Layout Engines".
* ICU's Bidi and shaping (u_shapeArabic()) APIs can be used at the core of such
* "Storage Layout Engines".
*
* <h3>General remarks about the API:</h3>
*
* In functions with an error code parameter,
* the <code>pErrorCode</code> pointer must be valid
* and the value that it points to must not indicate a failure before
* the function call. Otherwise, the function returns immediately.
* After the function call, the value indicates success or failure.<p>
*
* The &quot;limit&quot; of a sequence of characters is the position just after their
* last character, i.e., one more than that position.<p>
*
* Some of the API functions provide access to &quot;runs&quot;.
* Such a &quot;run&quot; is defined as a sequence of characters
* that are at the same embedding level
* after performing the Bidi algorithm.<p>
*
* @author Markus W. Scherer
* @version 1.0
*
*
* <h4> Sample code for the ICU Bidi API </h4>
*
* <h5>Rendering a paragraph with the ICU Bidi API</h5>
*
* This is (hypothetical) sample code that illustrates
* how the ICU Bidi API could be used to render a paragraph of text.
* Rendering code depends highly on the graphics system,
* therefore this sample code must make a lot of assumptions,
* which may or may not match any existing graphics system's properties.
*
* <p>The basic assumptions are:</p>
* <ul>
* <li>Rendering is done from left to right on a horizontal line.</li>
* <li>A run of single-style, unidirectional text can be rendered at once.</li>
* <li>Such a run of text is passed to the graphics system with
*     characters (code units) in logical order.</li>
* <li>The line-breaking algorithm is very complicated
*     and Locale-dependent -
*     and therefore its implementation omitted from this sample code.</li>
* </ul>
*
* <pre>
* \code
*#include <unicode/ubidi.h>
*
*typedef enum {
*     styleNormal=0, styleSelected=1,
*     styleBold=2, styleItalics=4,
*     styleSuper=8, styleSub=16
*} Style;
*
*typedef struct { int32_t limit; Style style; } StyleRun;
*
*int getTextWidth(const UChar *text, int32_t start, int32_t limit,
*                  const StyleRun *styleRuns, int styleRunCount);
*
* // set *pLimit and *pStyleRunLimit for a line
* // from text[start] and from styleRuns[styleRunStart]
* // using ubidi_getLogicalRun(para, ...)
*void getLineBreak(const UChar *text, int32_t start, int32_t *pLimit,
*                  UBiDi *para,
*                  const StyleRun *styleRuns, int styleRunStart, int *pStyleRunLimit,
*                  int *pLineWidth);
*
* // render runs on a line sequentially, always from left to right
*
* // prepare rendering a new line
* void startLine(UBiDiDirection textDirection, int lineWidth);
*
* // render a run of text and advance to the right by the run width
* // the text[start..limit-1] is always in logical order
* void renderRun(const UChar *text, int32_t start, int32_t limit,
*               UBiDiDirection textDirection, Style style);
*
* // We could compute a cross-product
* // from the style runs with the directional runs
* // and then reorder it.
* // Instead, here we iterate over each run type
* // and render the intersections -
* // with shortcuts in simple (and common) cases.
* // renderParagraph() is the main function.
*
* // render a directional run with
* // (possibly) multiple style runs intersecting with it
* void renderDirectionalRun(const UChar *text,
*                           int32_t start, int32_t limit,
*                           UBiDiDirection direction,
*                           const StyleRun *styleRuns, int styleRunCount) {
*     int i;
*
*     // iterate over style runs
*     if(direction==UBIDI_LTR) {
*         int styleLimit;
*
*         for(i=0; i<styleRunCount; ++i) {
*             styleLimit=styleRuns[i].limit;
*             if(start<styleLimit) {
*                 if(styleLimit>limit) { styleLimit=limit; }
*                 renderRun(text, start, styleLimit,
*                           direction, styleRuns[i].style);
*                 if(styleLimit==limit) { break; }
*                 start=styleLimit;
*             }
*         }
*     } else {
*         int styleStart;
*
*         for(i=styleRunCount-1; i>=0; --i) {
*             if(i>0) {
*                 styleStart=styleRuns[i-1].limit;
*             } else {
*                 styleStart=0;
*             }
*             if(limit>=styleStart) {
*                 if(styleStart<start) { styleStart=start; }
*                 renderRun(text, styleStart, limit,
*                           direction, styleRuns[i].style);
*                 if(styleStart==start) { break; }
*                 limit=styleStart;
*             }
*         }
*     }
* }
*
* // the line object represents text[start..limit-1]
* void renderLine(UBiDi *line, const UChar *text,
*                 int32_t start, int32_t limit,
*                 const StyleRun *styleRuns, int styleRunCount,
*                 UErrorCode *pErrorCode) {
*     UBiDiDirection direction=ubidi_getDirection(line);
*     if(direction!=UBIDI_MIXED) {
*         // unidirectional
*         if(styleRunCount<=1) {
*             renderRun(text, start, limit, direction, styleRuns[0].style);
*         } else {
*             renderDirectionalRun(text, start, limit,
*                                  direction, styleRuns, styleRunCount);
*         }
*     } else {
*         // mixed-directional
*         int32_t count, i, length;
*         UBiDiLevel level;
*
*         count=ubidi_countRuns(line, pErrorCode);
*         if(U_SUCCESS(*pErrorCode)) {
*             if(styleRunCount<=1) {
*                 Style style=styleRuns[0].style;
*
*                 // iterate over directional runs
*                for(i=0; i<count; ++i) {
*                    direction=ubidi_getVisualRun(line, i, &start, &length);
*                     renderRun(text, start, start+length, direction, style);
*                }
*             } else {
*                 int32_t j;
*
*                 // iterate over both directional and style runs
*                 for(i=0; i<count; ++i) {
*                     direction=ubidi_getVisualRun(line, i, &start, &length);
*                     renderDirectionalRun(text, start, start+length,
*                                          direction, styleRuns, styleRunCount);
*                 }
*             }
*         }
*     }
* }
*
*void renderParagraph(const UChar *text, int32_t length,
*                     UBiDiDirection textDirection,
*                      const StyleRun *styleRuns, int styleRunCount,
*                      int lineWidth,
*                      UErrorCode *pErrorCode) {
*     UBiDi *para;
*
*     if(pErrorCode==NULL || U_FAILURE(*pErrorCode) || length<=0) {
*         return;
*     }
*
*     para=ubidi_openSized(length, 0, pErrorCode);
*     if(para==NULL) { return; }
*
*     ubidi_setPara(para, text, length,
*                   textDirection ? UBIDI_DEFAULT_RTL : UBIDI_DEFAULT_LTR,
*                   NULL, pErrorCode);
*     if(U_SUCCESS(*pErrorCode)) {
*         UBiDiLevel paraLevel=1&ubidi_getParaLevel(para);
*         StyleRun styleRun={ length, styleNormal };
*         int width;
*
*         if(styleRuns==NULL || styleRunCount<=0) {
*            styleRunCount=1;
*             styleRuns=&styleRun;
*         }
*
*        // assume styleRuns[styleRunCount-1].limit>=length
*
*         width=getTextWidth(text, 0, length, styleRuns, styleRunCount);
*         if(width<=lineWidth) {
*             // everything fits onto one line
*
*            // prepare rendering a new line from either left or right
*             startLine(paraLevel, width);
*
*             renderLine(para, text, 0, length,
*                        styleRuns, styleRunCount, pErrorCode);
*         } else {
*             UBiDi *line;
*
*             // we need to render several lines
*             line=ubidi_openSized(length, 0, pErrorCode);
*             if(line!=NULL) {
*                 int32_t start=0, limit;
*                 int styleRunStart=0, styleRunLimit;
*
*                 for(;;) {
*                     limit=length;
*                     styleRunLimit=styleRunCount;
*                     getLineBreak(text, start, &limit, para,
*                                  styleRuns, styleRunStart, &styleRunLimit,
*                                 &width);
*                     ubidi_setLine(para, start, limit, line, pErrorCode);
*                     if(U_SUCCESS(*pErrorCode)) {
*                         // prepare rendering a new line
*                         // from either left or right
*                         startLine(paraLevel, width);
*
*                         renderLine(line, text, start, limit,
*                                    styleRuns+styleRunStart,
*                                    styleRunLimit-styleRunStart, pErrorCode);
*                     }
*                     if(limit==length) { break; }
*                     start=limit;
*                     styleRunStart=styleRunLimit-1;
*                     if(start>=styleRuns[styleRunStart].limit) {
*                         ++styleRunStart;
*                     }
*                 }
*
*                 ubidi_close(line);
*             }
*        }
*    }
*
*     ubidi_close(para);
*}
*\endcode
* </pre>
*/

/*DOCXX_TAG*/
/*@{*/

/**
* UBiDiLevel is the type of the level values in this
* Bidi implementation.
* It holds an embedding level and indicates the visual direction
* by its bit&nbsp;0 (even/odd value).<p>
*
* It can also hold non-level values for the
* <code>paraLevel</code> and <code>embeddingLevels</code>
* arguments of <code>ubidi_setPara()</code>; there:
* <ul>
* <li>bit&nbsp;7 of an <code>embeddingLevels[]</code>
* value indicates whether the using application is
* specifying the level of a character to <i>override</i> whatever the
* Bidi implementation would resolve it to.</li>
* <li><code>paraLevel</code> can be set to the
* pseudo-level values <code>UBIDI_DEFAULT_LTR</code>
* and <code>UBIDI_DEFAULT_RTL</code>.</li>
* </ul>
*
* @see ubidi_setPara
*
* <p>The related constants are not real, valid level values.
* <code>UBIDI_DEFAULT_XXX</code> can be used to specify
* a default for the paragraph level for
* when the <code>ubidi_setPara()</code> function
* shall determine it but there is no
* strongly typed character in the input.<p>
*
* Note that the value for <code>UBIDI_DEFAULT_LTR</code> is even
* and the one for <code>UBIDI_DEFAULT_RTL</code> is odd,
* just like with normal LTR and RTL level values -
* these special values are designed that way. Also, the implementation
* assumes that UBIDI_MAX_EXPLICIT_LEVEL is odd.
*
* Note: The numeric values of the related constants will not change:
* They are tied to the use of 7-bit byte values (plus the override bit)
* and of the UBiDiLevel=uint8_t data type in this API.
*
* @see UBIDI_DEFAULT_LTR
* @see UBIDI_DEFAULT_RTL
* @see UBIDI_LEVEL_OVERRIDE
* @see UBIDI_MAX_EXPLICIT_LEVEL
* @stable ICU 2.0
*/
typedef uint8_t UBiDiLevel;

/** Paragraph level setting.<p>
*
* Constant indicating that the base direction depends on the first strong
* directional character in the text according to the Unicode Bidirectional
* Algorithm. If no strong directional character is present,
* then set the paragraph level to 0 (left-to-right).<p>
*
* If this value is used in conjunction with reordering modes
* <code>UBIDI_REORDER_INVERSE_LIKE_DIRECT</code> or
* <code>UBIDI_REORDER_INVERSE_FOR_NUMBERS_SPECIAL</code>, the text to reorder
* is assumed to be visual LTR, and the text after reordering is required
* to be the corresponding logical string with appropriate contextual
* direction. The direction of the result string will be RTL if either
* the righmost or leftmost strong character of the source text is RTL
* or Arabic Letter, the direction will be LTR otherwise.<p>
*
* If reordering option <code>UBIDI_OPTION_INSERT_MARKS</code> is set, an RLM may
* be added at the beginning of the result string to ensure round trip
* (that the result string, when reordered back to visual, will produce
* the original source text).
* @see UBIDI_REORDER_INVERSE_LIKE_DIRECT
* @see UBIDI_REORDER_INVERSE_FOR_NUMBERS_SPECIAL
* @stable ICU 2.0
*/
#define UBIDI_DEFAULT_LTR 0xfe

/** Paragraph level setting.<p>
*
* Constant indicating that the base direction depends on the first strong
* directional character in the text according to the Unicode Bidirectional
* Algorithm. If no strong directional character is present,
* then set the paragraph level to 1 (right-to-left).<p>
*
* If this value is used in conjunction with reordering modes
* <code>UBIDI_REORDER_INVERSE_LIKE_DIRECT</code> or
* <code>UBIDI_REORDER_INVERSE_FOR_NUMBERS_SPECIAL</code>, the text to reorder
* is assumed to be visual LTR, and the text after reordering is required
* to be the corresponding logical string with appropriate contextual
* direction. The direction of the result string will be RTL if either
* the righmost or leftmost strong character of the source text is RTL
* or Arabic Letter, or if the text contains no strong character;
* the direction will be LTR otherwise.<p>
*
* If reordering option <code>UBIDI_OPTION_INSERT_MARKS</code> is set, an RLM may
* be added at the beginning of the result string to ensure round trip
* (that the result string, when reordered back to visual, will produce
* the original source text).
* @see UBIDI_REORDER_INVERSE_LIKE_DIRECT
* @see UBIDI_REORDER_INVERSE_FOR_NUMBERS_SPECIAL
* @stable ICU 2.0
*/
#define UBIDI_DEFAULT_RTL 0xff

/**
* Maximum explicit embedding level.
* Same as the max_depth value in the
* <a href="http://www.unicode.org/reports/tr9/#BD2">Unicode Bidirectional Algorithm</a>.
* (The maximum resolved level can be up to <code>UBIDI_MAX_EXPLICIT_LEVEL+1</code>).
* @stable ICU 2.0
*/
#define UBIDI_MAX_EXPLICIT_LEVEL 125

/** Bit flag for level input.
*  Overrides directional properties.
* @stable ICU 2.0
*/
#define UBIDI_LEVEL_OVERRIDE 0x80

/**
* Special value which can be returned by the mapping functions when a logical
* index has no corresponding visual index or vice-versa. This may happen
* for the logical-to-visual mapping of a Bidi control when option
* <code>#UBIDI_OPTION_REMOVE_CONTROLS</code> is specified. This can also happen
* for the visual-to-logical mapping of a Bidi mark (LRM or RLM) inserted
* by option <code>#UBIDI_OPTION_INSERT_MARKS</code>.
* @see ubidi_getVisualIndex
* @see ubidi_getVisualMap
* @see ubidi_getLogicalIndex
* @see ubidi_getLogicalMap
* @stable ICU 3.6
*/
#define UBIDI_MAP_NOWHERE   (-1)

/**
* <code>UBiDiDirection</code> values indicate the text direction.
* @stable ICU 2.0
*/
enum UBiDiDirection {
 /** Left-to-right text. This is a 0 value.
  * <ul>
  * <li>As return value for <code>ubidi_getDirection()</code>, it means
  *     that the source string contains no right-to-left characters, or
  *     that the source string is empty and the paragraph level is even.
  * <li> As return value for <code>ubidi_getBaseDirection()</code>, it
  *      means that the first strong character of the source string has
  *      a left-to-right direction.
  * </ul>
  * @stable ICU 2.0
  */
 UBIDI_LTR,
 /** Right-to-left text. This is a 1 value.
  * <ul>
  * <li>As return value for <code>ubidi_getDirection()</code>, it means
  *     that the source string contains no left-to-right characters, or
  *     that the source string is empty and the paragraph level is odd.
  * <li> As return value for <code>ubidi_getBaseDirection()</code>, it
  *      means that the first strong character of the source string has
  *      a right-to-left direction.
  * </ul>
  * @stable ICU 2.0
  */
 UBIDI_RTL,
 /** Mixed-directional text.
  * <p>As return value for <code>ubidi_getDirection()</code>, it means
  *    that the source string contains both left-to-right and
  *    right-to-left characters.
  * @stable ICU 2.0
  */
 UBIDI_MIXED,
 /** No strongly directional text.
  * <p>As return value for <code>ubidi_getBaseDirection()</code>, it means
  *    that the source string is missing or empty, or contains neither left-to-right
  *    nor right-to-left characters.
  * @stable ICU 4.6
  */
 UBIDI_NEUTRAL
};

/** @stable ICU 2.0 */
typedef enum UBiDiDirection UBiDiDirection;

/**
* Forward declaration of the <code>UBiDi</code> structure for the declaration of
* the API functions. Its fields are implementation-specific.<p>
* This structure holds information about a paragraph (or multiple paragraphs)
* of text with Bidi-algorithm-related details, or about one line of
* such a paragraph.<p>
* Reordering can be done on a line, or on one or more paragraphs which are
* then interpreted each as one single line.
* @stable ICU 2.0
*/
struct UBiDi;

/** @stable ICU 2.0 */
typedef struct UBiDi UBiDi;

/**
* Allocate a <code>UBiDi</code> structure.
* Such an object is initially empty. It is assigned
* the Bidi properties of a piece of text containing one or more paragraphs
* by <code>ubidi_setPara()</code>
* or the Bidi properties of a line within a paragraph by
* <code>ubidi_setLine()</code>.<p>
* This object can be reused for as long as it is not deallocated
* by calling <code>ubidi_close()</code>.<p>
* <code>ubidi_setPara()</code> and <code>ubidi_setLine()</code> will allocate
* additional memory for internal structures as necessary.
*
* @return An empty <code>UBiDi</code> object.
* @stable ICU 2.0
*/
U_CAPI UBiDi * U_EXPORT2
ubidi_open(void);

/**
* Allocate a <code>UBiDi</code> structure with preallocated memory
* for internal structures.
* This function provides a <code>UBiDi</code> object like <code>ubidi_open()</code>
* with no arguments, but it also preallocates memory for internal structures
* according to the sizings supplied by the caller.<p>
* Subsequent functions will not allocate any more memory, and are thus
* guaranteed not to fail because of lack of memory.<p>
* The preallocation can be limited to some of the internal memory
* by setting some values to 0 here. That means that if, e.g.,
* <code>maxRunCount</code> cannot be reasonably predetermined and should not
* be set to <code>maxLength</code> (the only failproof value) to avoid
* wasting memory, then <code>maxRunCount</code> could be set to 0 here
* and the internal structures that are associated with it will be allocated
* on demand, just like with <code>ubidi_open()</code>.
*
* @param maxLength is the maximum text or line length that internal memory
*        will be preallocated for. An attempt to associate this object with a
*        longer text will fail, unless this value is 0, which leaves the allocation
*        up to the implementation.
*
* @param maxRunCount is the maximum anticipated number of same-level runs
*        that internal memory will be preallocated for. An attempt to access
*        visual runs on an object that was not preallocated for as many runs
*        as the text was actually resolved to will fail,
*        unless this value is 0, which leaves the allocation up to the implementation.<br><br>
*        The number of runs depends on the actual text and maybe anywhere between
*        1 and <code>maxLength</code>. It is typically small.
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @return An empty <code>UBiDi</code> object with preallocated memory.
* @stable ICU 2.0
*/
U_CAPI UBiDi * U_EXPORT2
ubidi_openSized(int32_t maxLength, int32_t maxRunCount, UErrorCode *pErrorCode);

/**
* <code>ubidi_close()</code> must be called to free the memory
* associated with a UBiDi object.<p>
*
* <strong>Important: </strong>
* A parent <code>UBiDi</code> object must not be destroyed or reused if
* it still has children.
* If a <code>UBiDi</code> object has become the <i>child</i>
* of another one (its <i>parent</i>) by calling
* <code>ubidi_setLine()</code>, then the child object must
* be destroyed (closed) or reused (by calling
* <code>ubidi_setPara()</code> or <code>ubidi_setLine()</code>)
* before the parent object.
*
* @param pBiDi is a <code>UBiDi</code> object.
*
* @see ubidi_setPara
* @see ubidi_setLine
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ubidi_close(UBiDi *pBiDi);

#if U_SHOW_CPLUSPLUS_API

U_NAMESPACE_BEGIN

/**
* \class LocalUBiDiPointer
* "Smart pointer" class, closes a UBiDi via ubidi_close().
* For most methods see the LocalPointerBase base class.
*
* @see LocalPointerBase
* @see LocalPointer
* @stable ICU 4.4
*/
U_DEFINE_LOCAL_OPEN_POINTER(LocalUBiDiPointer, UBiDi, ubidi_close);

U_NAMESPACE_END

#endif

/**
* Modify the operation of the Bidi algorithm such that it
* approximates an "inverse Bidi" algorithm. This function
* must be called before <code>ubidi_setPara()</code>.
*
* <p>The normal operation of the Bidi algorithm as described
* in the Unicode Technical Report is to take text stored in logical
* (keyboard, typing) order and to determine the reordering of it for visual
* rendering.
* Some legacy systems store text in visual order, and for operations
* with standard, Unicode-based algorithms, the text needs to be transformed
* to logical order. This is effectively the inverse algorithm of the
* described Bidi algorithm. Note that there is no standard algorithm for
* this "inverse Bidi" and that the current implementation provides only an
* approximation of "inverse Bidi".</p>
*
* <p>With <code>isInverse</code> set to <code>true</code>,
* this function changes the behavior of some of the subsequent functions
* in a way that they can be used for the inverse Bidi algorithm.
* Specifically, runs of text with numeric characters will be treated in a
* special way and may need to be surrounded with LRM characters when they are
* written in reordered sequence.</p>
*
* <p>Output runs should be retrieved using <code>ubidi_getVisualRun()</code>.
* Since the actual input for "inverse Bidi" is visually ordered text and
* <code>ubidi_getVisualRun()</code> gets the reordered runs, these are actually
* the runs of the logically ordered output.</p>
*
* <p>Calling this function with argument <code>isInverse</code> set to
* <code>true</code> is equivalent to calling
* <code>ubidi_setReorderingMode</code> with argument
* <code>reorderingMode</code>
* set to <code>#UBIDI_REORDER_INVERSE_NUMBERS_AS_L</code>.<br>
* Calling this function with argument <code>isInverse</code> set to
* <code>false</code> is equivalent to calling
* <code>ubidi_setReorderingMode</code> with argument
* <code>reorderingMode</code>
* set to <code>#UBIDI_REORDER_DEFAULT</code>.
*
* @param pBiDi is a <code>UBiDi</code> object.
*
* @param isInverse specifies "forward" or "inverse" Bidi operation.
*
* @see ubidi_setPara
* @see ubidi_writeReordered
* @see ubidi_setReorderingMode
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ubidi_setInverse(UBiDi *pBiDi, UBool isInverse);

/**
* Is this Bidi object set to perform the inverse Bidi algorithm?
* <p>Note: calling this function after setting the reordering mode with
* <code>ubidi_setReorderingMode</code> will return <code>true</code> if the
* reordering mode was set to <code>#UBIDI_REORDER_INVERSE_NUMBERS_AS_L</code>,
* <code>false</code> for all other values.</p>
*
* @param pBiDi is a <code>UBiDi</code> object.
* @return true if the Bidi object is set to perform the inverse Bidi algorithm
* by handling numbers as L.
*
* @see ubidi_setInverse
* @see ubidi_setReorderingMode
* @stable ICU 2.0
*/

U_CAPI UBool U_EXPORT2
ubidi_isInverse(UBiDi *pBiDi);

/**
* Specify whether block separators must be allocated level zero,
* so that successive paragraphs will progress from left to right.
* This function must be called before <code>ubidi_setPara()</code>.
* Paragraph separators (B) may appear in the text.  Setting them to level zero
* means that all paragraph separators (including one possibly appearing
* in the last text position) are kept in the reordered text after the text
* that they follow in the source text.
* When this feature is not enabled, a paragraph separator at the last
* position of the text before reordering will go to the first position
* of the reordered text when the paragraph level is odd.
*
* @param pBiDi is a <code>UBiDi</code> object.
*
* @param orderParagraphsLTR specifies whether paragraph separators (B) must
* receive level 0, so that successive paragraphs progress from left to right.
*
* @see ubidi_setPara
* @stable ICU 3.4
*/
U_CAPI void U_EXPORT2
ubidi_orderParagraphsLTR(UBiDi *pBiDi, UBool orderParagraphsLTR);

/**
* Is this Bidi object set to allocate level 0 to block separators so that
* successive paragraphs progress from left to right?
*
* @param pBiDi is a <code>UBiDi</code> object.
* @return true if the Bidi object is set to allocate level 0 to block
*         separators.
*
* @see ubidi_orderParagraphsLTR
* @stable ICU 3.4
*/
U_CAPI UBool U_EXPORT2
ubidi_isOrderParagraphsLTR(UBiDi *pBiDi);

/**
* <code>UBiDiReorderingMode</code> values indicate which variant of the Bidi
* algorithm to use.
*
* @see ubidi_setReorderingMode
* @stable ICU 3.6
*/
typedef enum UBiDiReorderingMode {
   /** Regular Logical to Visual Bidi algorithm according to Unicode.
     * This is a 0 value.
     * @stable ICU 3.6 */
   UBIDI_REORDER_DEFAULT = 0,
   /** Logical to Visual algorithm which handles numbers in a way which
     * mimics the behavior of Windows XP.
     * @stable ICU 3.6 */
   UBIDI_REORDER_NUMBERS_SPECIAL,
   /** Logical to Visual algorithm grouping numbers with adjacent R characters
     * (reversible algorithm).
     * @stable ICU 3.6 */
   UBIDI_REORDER_GROUP_NUMBERS_WITH_R,
   /** Reorder runs only to transform a Logical LTR string to the Logical RTL
     * string with the same display, or vice-versa.<br>
     * If this mode is set together with option
     * <code>#UBIDI_OPTION_INSERT_MARKS</code>, some Bidi controls in the source
     * text may be removed and other controls may be added to produce the
     * minimum combination which has the required display.
     * @stable ICU 3.6 */
   UBIDI_REORDER_RUNS_ONLY,
   /** Visual to Logical algorithm which handles numbers like L
     * (same algorithm as selected by <code>ubidi_setInverse(true)</code>.
     * @see ubidi_setInverse
     * @stable ICU 3.6 */
   UBIDI_REORDER_INVERSE_NUMBERS_AS_L,
   /** Visual to Logical algorithm equivalent to the regular Logical to Visual
     * algorithm.
     * @stable ICU 3.6 */
   UBIDI_REORDER_INVERSE_LIKE_DIRECT,
   /** Inverse Bidi (Visual to Logical) algorithm for the
     * <code>UBIDI_REORDER_NUMBERS_SPECIAL</code> Bidi algorithm.
     * @stable ICU 3.6 */
   UBIDI_REORDER_INVERSE_FOR_NUMBERS_SPECIAL,
#ifndef U_HIDE_DEPRECATED_API
   /**
    * Number of values for reordering mode.
    * @deprecated ICU 58 The numeric value may change over time, see ICU ticket #12420.
    */
   UBIDI_REORDER_COUNT
#endif  // U_HIDE_DEPRECATED_API
} UBiDiReorderingMode;

/**
* Modify the operation of the Bidi algorithm such that it implements some
* variant to the basic Bidi algorithm or approximates an "inverse Bidi"
* algorithm, depending on different values of the "reordering mode".
* This function must be called before <code>ubidi_setPara()</code>, and stays
* in effect until called again with a different argument.
*
* <p>The normal operation of the Bidi algorithm as described
* in the Unicode Standard Annex #9 is to take text stored in logical
* (keyboard, typing) order and to determine how to reorder it for visual
* rendering.</p>
*
* <p>With the reordering mode set to a value other than
* <code>#UBIDI_REORDER_DEFAULT</code>, this function changes the behavior of
* some of the subsequent functions in a way such that they implement an
* inverse Bidi algorithm or some other algorithm variants.</p>
*
* <p>Some legacy systems store text in visual order, and for operations
* with standard, Unicode-based algorithms, the text needs to be transformed
* into logical order. This is effectively the inverse algorithm of the
* described Bidi algorithm. Note that there is no standard algorithm for
* this "inverse Bidi", so a number of variants are implemented here.</p>
*
* <p>In other cases, it may be desirable to emulate some variant of the
* Logical to Visual algorithm (e.g. one used in MS Windows), or perform a
* Logical to Logical transformation.</p>
*
* <ul>
* <li>When the reordering mode is set to <code>#UBIDI_REORDER_DEFAULT</code>,
* the standard Bidi Logical to Visual algorithm is applied.</li>
*
* <li>When the reordering mode is set to
* <code>#UBIDI_REORDER_NUMBERS_SPECIAL</code>,
* the algorithm used to perform Bidi transformations when calling
* <code>ubidi_setPara</code> should approximate the algorithm used in
* Microsoft Windows XP rather than strictly conform to the Unicode Bidi
* algorithm.
* <br>
* The differences between the basic algorithm and the algorithm addressed
* by this option are as follows:
* <ul>
*   <li>Within text at an even embedding level, the sequence "123AB"
*   (where AB represent R or AL letters) is transformed to "123BA" by the
*   Unicode algorithm and to "BA123" by the Windows algorithm.</li>
*   <li>Arabic-Indic numbers (AN) are handled by the Windows algorithm just
*   like regular numbers (EN).</li>
* </ul></li>
*
* <li>When the reordering mode is set to
* <code>#UBIDI_REORDER_GROUP_NUMBERS_WITH_R</code>,
* numbers located between LTR text and RTL text are associated with the RTL
* text. For instance, an LTR paragraph with content "abc 123 DEF" (where
* upper case letters represent RTL characters) will be transformed to
* "abc FED 123" (and not "abc 123 FED"), "DEF 123 abc" will be transformed
* to "123 FED abc" and "123 FED abc" will be transformed to "DEF 123 abc".
* This makes the algorithm reversible and makes it useful when round trip
* (from visual to logical and back to visual) must be achieved without
* adding LRM characters. However, this is a variation from the standard
* Unicode Bidi algorithm.<br>
* The source text should not contain Bidi control characters other than LRM
* or RLM.</li>
*
* <li>When the reordering mode is set to
* <code>#UBIDI_REORDER_RUNS_ONLY</code>,
* a "Logical to Logical" transformation must be performed:
* <ul>
* <li>If the default text level of the source text (argument <code>paraLevel</code>
* in <code>ubidi_setPara</code>) is even, the source text will be handled as
* LTR logical text and will be transformed to the RTL logical text which has
* the same LTR visual display.</li>
* <li>If the default level of the source text is odd, the source text
* will be handled as RTL logical text and will be transformed to the
* LTR logical text which has the same LTR visual display.</li>
* </ul>
* This mode may be needed when logical text which is basically Arabic or
* Hebrew, with possible included numbers or phrases in English, has to be
* displayed as if it had an even embedding level (this can happen if the
* displaying application treats all text as if it was basically LTR).
* <br>
* This mode may also be needed in the reverse case, when logical text which is
* basically English, with possible included phrases in Arabic or Hebrew, has to
* be displayed as if it had an odd embedding level.
* <br>
* Both cases could be handled by adding LRE or RLE at the head of the text,
* if the display subsystem supports these formatting controls. If it does not,
* the problem may be handled by transforming the source text in this mode
* before displaying it, so that it will be displayed properly.<br>
* The source text should not contain Bidi control characters other than LRM
* or RLM.</li>
*
* <li>When the reordering mode is set to
* <code>#UBIDI_REORDER_INVERSE_NUMBERS_AS_L</code>, an "inverse Bidi" algorithm
* is applied.
* Runs of text with numeric characters will be treated like LTR letters and
* may need to be surrounded with LRM characters when they are written in
* reordered sequence (the option <code>#UBIDI_INSERT_LRM_FOR_NUMERIC</code> can
* be used with function <code>ubidi_writeReordered</code> to this end. This
* mode is equivalent to calling <code>ubidi_setInverse()</code> with
* argument <code>isInverse</code> set to <code>true</code>.</li>
*
* <li>When the reordering mode is set to
* <code>#UBIDI_REORDER_INVERSE_LIKE_DIRECT</code>, the "direct" Logical to Visual
* Bidi algorithm is used as an approximation of an "inverse Bidi" algorithm.
* This mode is similar to mode <code>#UBIDI_REORDER_INVERSE_NUMBERS_AS_L</code>
* but is closer to the regular Bidi algorithm.
* <br>
* For example, an LTR paragraph with the content "FED 123 456 CBA" (where
* upper case represents RTL characters) will be transformed to
* "ABC 456 123 DEF", as opposed to "DEF 123 456 ABC"
* with mode <code>UBIDI_REORDER_INVERSE_NUMBERS_AS_L</code>.<br>
* When used in conjunction with option
* <code>#UBIDI_OPTION_INSERT_MARKS</code>, this mode generally
* adds Bidi marks to the output significantly more sparingly than mode
* <code>#UBIDI_REORDER_INVERSE_NUMBERS_AS_L</code> with option
* <code>#UBIDI_INSERT_LRM_FOR_NUMERIC</code> in calls to
* <code>ubidi_writeReordered</code>.</li>
*
* <li>When the reordering mode is set to
* <code>#UBIDI_REORDER_INVERSE_FOR_NUMBERS_SPECIAL</code>, the Logical to Visual
* Bidi algorithm used in Windows XP is used as an approximation of an "inverse Bidi" algorithm.
* <br>
* For example, an LTR paragraph with the content "abc FED123" (where
* upper case represents RTL characters) will be transformed to "abc 123DEF."</li>
* </ul>
*
* <p>In all the reordering modes specifying an "inverse Bidi" algorithm
* (i.e. those with a name starting with <code>UBIDI_REORDER_INVERSE</code>),
* output runs should be retrieved using
* <code>ubidi_getVisualRun()</code>, and the output text with
* <code>ubidi_writeReordered()</code>. The caller should keep in mind that in
* "inverse Bidi" modes the input is actually visually ordered text and
* reordered output returned by <code>ubidi_getVisualRun()</code> or
* <code>ubidi_writeReordered()</code> are actually runs or character string
* of logically ordered output.<br>
* For all the "inverse Bidi" modes, the source text should not contain
* Bidi control characters other than LRM or RLM.</p>
*
* <p>Note that option <code>#UBIDI_OUTPUT_REVERSE</code> of
* <code>ubidi_writeReordered</code> has no useful meaning and should not be
* used in conjunction with any value of the reordering mode specifying
* "inverse Bidi" or with value <code>UBIDI_REORDER_RUNS_ONLY</code>.
*
* @param pBiDi is a <code>UBiDi</code> object.
* @param reorderingMode specifies the required variant of the Bidi algorithm.
*
* @see UBiDiReorderingMode
* @see ubidi_setInverse
* @see ubidi_setPara
* @see ubidi_writeReordered
* @stable ICU 3.6
*/
U_CAPI void U_EXPORT2
ubidi_setReorderingMode(UBiDi *pBiDi, UBiDiReorderingMode reorderingMode);

/**
* What is the requested reordering mode for a given Bidi object?
*
* @param pBiDi is a <code>UBiDi</code> object.
* @return the current reordering mode of the Bidi object
* @see ubidi_setReorderingMode
* @stable ICU 3.6
*/
U_CAPI UBiDiReorderingMode U_EXPORT2
ubidi_getReorderingMode(UBiDi *pBiDi);

/**
* <code>UBiDiReorderingOption</code> values indicate which options are
* specified to affect the Bidi algorithm.
*
* @see ubidi_setReorderingOptions
* @stable ICU 3.6
*/
typedef enum UBiDiReorderingOption {
   /**
    * option value for <code>ubidi_setReorderingOptions</code>:
    * disable all the options which can be set with this function
    * @see ubidi_setReorderingOptions
    * @stable ICU 3.6
    */
   UBIDI_OPTION_DEFAULT = 0,

   /**
    * option bit for <code>ubidi_setReorderingOptions</code>:
    * insert Bidi marks (LRM or RLM) when needed to ensure correct result of
    * a reordering to a Logical order
    *
    * <p>This option must be set or reset before calling
    * <code>ubidi_setPara</code>.</p>
    *
    * <p>This option is significant only with reordering modes which generate
    * a result with Logical order, specifically:</p>
    * <ul>
    *   <li><code>#UBIDI_REORDER_RUNS_ONLY</code></li>
    *   <li><code>#UBIDI_REORDER_INVERSE_NUMBERS_AS_L</code></li>
    *   <li><code>#UBIDI_REORDER_INVERSE_LIKE_DIRECT</code></li>
    *   <li><code>#UBIDI_REORDER_INVERSE_FOR_NUMBERS_SPECIAL</code></li>
    * </ul>
    *
    * <p>If this option is set in conjunction with reordering mode
    * <code>#UBIDI_REORDER_INVERSE_NUMBERS_AS_L</code> or with calling
    * <code>ubidi_setInverse(true)</code>, it implies
    * option <code>#UBIDI_INSERT_LRM_FOR_NUMERIC</code>
    * in calls to function <code>ubidi_writeReordered()</code>.</p>
    *
    * <p>For other reordering modes, a minimum number of LRM or RLM characters
    * will be added to the source text after reordering it so as to ensure
    * round trip, i.e. when applying the inverse reordering mode on the
    * resulting logical text with removal of Bidi marks
    * (option <code>#UBIDI_OPTION_REMOVE_CONTROLS</code> set before calling
    * <code>ubidi_setPara()</code> or option <code>#UBIDI_REMOVE_BIDI_CONTROLS</code>
    * in <code>ubidi_writeReordered</code>), the result will be identical to the
    * source text in the first transformation.
    *
    * <p>This option will be ignored if specified together with option
    * <code>#UBIDI_OPTION_REMOVE_CONTROLS</code>. It inhibits option
    * <code>UBIDI_REMOVE_BIDI_CONTROLS</code> in calls to function
    * <code>ubidi_writeReordered()</code> and it implies option
    * <code>#UBIDI_INSERT_LRM_FOR_NUMERIC</code> in calls to function
    * <code>ubidi_writeReordered()</code> if the reordering mode is
    * <code>#UBIDI_REORDER_INVERSE_NUMBERS_AS_L</code>.</p>
    *
    * @see ubidi_setReorderingMode
    * @see ubidi_setReorderingOptions
    * @stable ICU 3.6
    */
   UBIDI_OPTION_INSERT_MARKS = 1,

   /**
    * option bit for <code>ubidi_setReorderingOptions</code>:
    * remove Bidi control characters
    *
    * <p>This option must be set or reset before calling
    * <code>ubidi_setPara</code>.</p>
    *
    * <p>This option nullifies option <code>#UBIDI_OPTION_INSERT_MARKS</code>.
    * It inhibits option <code>#UBIDI_INSERT_LRM_FOR_NUMERIC</code> in calls
    * to function <code>ubidi_writeReordered()</code> and it implies option
    * <code>#UBIDI_REMOVE_BIDI_CONTROLS</code> in calls to that function.</p>
    *
    * @see ubidi_setReorderingMode
    * @see ubidi_setReorderingOptions
    * @stable ICU 3.6
    */
   UBIDI_OPTION_REMOVE_CONTROLS = 2,

   /**
    * option bit for <code>ubidi_setReorderingOptions</code>:
    * process the output as part of a stream to be continued
    *
    * <p>This option must be set or reset before calling
    * <code>ubidi_setPara</code>.</p>
    *
    * <p>This option specifies that the caller is interested in processing large
    * text object in parts.
    * The results of the successive calls are expected to be concatenated by the
    * caller. Only the call for the last part will have this option bit off.</p>
    *
    * <p>When this option bit is on, <code>ubidi_setPara()</code> may process
    * less than the full source text in order to truncate the text at a meaningful
    * boundary. The caller should call <code>ubidi_getProcessedLength()</code>
    * immediately after calling <code>ubidi_setPara()</code> in order to
    * determine how much of the source text has been processed.
    * Source text beyond that length should be resubmitted in following calls to
    * <code>ubidi_setPara</code>. The processed length may be less than
    * the length of the source text if a character preceding the last character of
    * the source text constitutes a reasonable boundary (like a block separator)
    * for text to be continued.<br>
    * If the last character of the source text constitutes a reasonable
    * boundary, the whole text will be processed at once.<br>
    * If nowhere in the source text there exists
    * such a reasonable boundary, the processed length will be zero.<br>
    * The caller should check for such an occurrence and do one of the following:
    * <ul><li>submit a larger amount of text with a better chance to include
    *         a reasonable boundary.</li>
    *     <li>resubmit the same text after turning off option
    *         <code>UBIDI_OPTION_STREAMING</code>.</li></ul>
    * In all cases, this option should be turned off before processing the last
    * part of the text.</p>
    *
    * <p>When the <code>UBIDI_OPTION_STREAMING</code> option is used,
    * it is recommended to call <code>ubidi_orderParagraphsLTR()</code> with
    * argument <code>orderParagraphsLTR</code> set to <code>true</code> before
    * calling <code>ubidi_setPara</code> so that later paragraphs may be
    * concatenated to previous paragraphs on the right.</p>
    *
    * @see ubidi_setReorderingMode
    * @see ubidi_setReorderingOptions
    * @see ubidi_getProcessedLength
    * @see ubidi_orderParagraphsLTR
    * @stable ICU 3.6
    */
   UBIDI_OPTION_STREAMING = 4
} UBiDiReorderingOption;

/**
* Specify which of the reordering options
* should be applied during Bidi transformations.
*
* @param pBiDi is a <code>UBiDi</code> object.
* @param reorderingOptions is a combination of zero or more of the following
* options:
* <code>#UBIDI_OPTION_DEFAULT</code>, <code>#UBIDI_OPTION_INSERT_MARKS</code>,
* <code>#UBIDI_OPTION_REMOVE_CONTROLS</code>, <code>#UBIDI_OPTION_STREAMING</code>.
*
* @see ubidi_getReorderingOptions
* @stable ICU 3.6
*/
U_CAPI void U_EXPORT2
ubidi_setReorderingOptions(UBiDi *pBiDi, uint32_t reorderingOptions);

/**
* What are the reordering options applied to a given Bidi object?
*
* @param pBiDi is a <code>UBiDi</code> object.
* @return the current reordering options of the Bidi object
* @see ubidi_setReorderingOptions
* @stable ICU 3.6
*/
U_CAPI uint32_t U_EXPORT2
ubidi_getReorderingOptions(UBiDi *pBiDi);

/**
* Set the context before a call to ubidi_setPara().<p>
*
* ubidi_setPara() computes the left-right directionality for a given piece
* of text which is supplied as one of its arguments. Sometimes this piece
* of text (the "main text") should be considered in context, because text
* appearing before ("prologue") and/or after ("epilogue") the main text
* may affect the result of this computation.<p>
*
* This function specifies the prologue and/or the epilogue for the next
* call to ubidi_setPara(). The characters specified as prologue and
* epilogue should not be modified by the calling program until the call
* to ubidi_setPara() has returned. If successive calls to ubidi_setPara()
* all need specification of a context, ubidi_setContext() must be called
* before each call to ubidi_setPara(). In other words, a context is not
* "remembered" after the following successful call to ubidi_setPara().<p>
*
* If a call to ubidi_setPara() specifies UBIDI_DEFAULT_LTR or
* UBIDI_DEFAULT_RTL as paraLevel and is preceded by a call to
* ubidi_setContext() which specifies a prologue, the paragraph level will
* be computed taking in consideration the text in the prologue.<p>
*
* When ubidi_setPara() is called without a previous call to
* ubidi_setContext, the main text is handled as if preceded and followed
* by strong directional characters at the current paragraph level.
* Calling ubidi_setContext() with specification of a prologue will change
* this behavior by handling the main text as if preceded by the last
* strong character appearing in the prologue, if any.
* Calling ubidi_setContext() with specification of an epilogue will change
* the behavior of ubidi_setPara() by handling the main text as if followed
* by the first strong character or digit appearing in the epilogue, if any.<p>
*
* Note 1: if <code>ubidi_setContext</code> is called repeatedly without
*         calling <code>ubidi_setPara</code>, the earlier calls have no effect,
*         only the last call will be remembered for the next call to
*         <code>ubidi_setPara</code>.<p>
*
* Note 2: calling <code>ubidi_setContext(pBiDi, NULL, 0, NULL, 0, &errorCode)</code>
*         cancels any previous setting of non-empty prologue or epilogue.
*         The next call to <code>ubidi_setPara()</code> will process no
*         prologue or epilogue.<p>
*
* Note 3: users must be aware that even after setting the context
*         before a call to ubidi_setPara() to perform e.g. a logical to visual
*         transformation, the resulting string may not be identical to what it
*         would have been if all the text, including prologue and epilogue, had
*         been processed together.<br>
* Example (upper case letters represent RTL characters):<br>
* &nbsp;&nbsp;prologue = "<code>abc DE</code>"<br>
* &nbsp;&nbsp;epilogue = none<br>
* &nbsp;&nbsp;main text = "<code>FGH xyz</code>"<br>
* &nbsp;&nbsp;paraLevel = UBIDI_LTR<br>
* &nbsp;&nbsp;display without prologue = "<code>HGF xyz</code>"
*             ("HGF" is adjacent to "xyz")<br>
* &nbsp;&nbsp;display with prologue = "<code>abc HGFED xyz</code>"
*             ("HGF" is not adjacent to "xyz")<br>
*
* @param pBiDi is a paragraph <code>UBiDi</code> object.
*
* @param prologue is a pointer to the text which precedes the text that
*        will be specified in a coming call to ubidi_setPara().
*        If there is no prologue to consider, then <code>proLength</code>
*        must be zero and this pointer can be NULL.
*
* @param proLength is the length of the prologue; if <code>proLength==-1</code>
*        then the prologue must be zero-terminated.
*        Otherwise proLength must be >= 0. If <code>proLength==0</code>, it means
*        that there is no prologue to consider.
*
* @param epilogue is a pointer to the text which follows the text that
*        will be specified in a coming call to ubidi_setPara().
*        If there is no epilogue to consider, then <code>epiLength</code>
*        must be zero and this pointer can be NULL.
*
* @param epiLength is the length of the epilogue; if <code>epiLength==-1</code>
*        then the epilogue must be zero-terminated.
*        Otherwise epiLength must be >= 0. If <code>epiLength==0</code>, it means
*        that there is no epilogue to consider.
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @see ubidi_setPara
* @stable ICU 4.8
*/
U_CAPI void U_EXPORT2
ubidi_setContext(UBiDi *pBiDi,
                const UChar *prologue, int32_t proLength,
                const UChar *epilogue, int32_t epiLength,
                UErrorCode *pErrorCode);

/**
* Perform the Unicode Bidi algorithm. It is defined in the
* <a href="http://www.unicode.org/unicode/reports/tr9/">Unicode Standard Annex #9</a>,
* version 13,
* also described in The Unicode Standard, Version 4.0 .<p>
*
* This function takes a piece of plain text containing one or more paragraphs,
* with or without externally specified embedding levels from <i>styled</i>
* text and computes the left-right-directionality of each character.<p>
*
* If the entire text is all of the same directionality, then
* the function may not perform all the steps described by the algorithm,
* i.e., some levels may not be the same as if all steps were performed.
* This is not relevant for unidirectional text.<br>
* For example, in pure LTR text with numbers the numbers would get
* a resolved level of 2 higher than the surrounding text according to
* the algorithm. This implementation may set all resolved levels to
* the same value in such a case.<p>
*
* The text can be composed of multiple paragraphs. Occurrence of a block
* separator in the text terminates a paragraph, and whatever comes next starts
* a new paragraph. The exception to this rule is when a Carriage Return (CR)
* is followed by a Line Feed (LF). Both CR and LF are block separators, but
* in that case, the pair of characters is considered as terminating the
* preceding paragraph, and a new paragraph will be started by a character
* coming after the LF.
*
* @param pBiDi A <code>UBiDi</code> object allocated with <code>ubidi_open()</code>
*        which will be set to contain the reordering information,
*        especially the resolved levels for all the characters in <code>text</code>.
*
* @param text is a pointer to the text that the Bidi algorithm will be performed on.
*        This pointer is stored in the UBiDi object and can be retrieved
*        with <code>ubidi_getText()</code>.<br>
*        <strong>Note:</strong> the text must be (at least) <code>length</code> long.
*
* @param length is the length of the text; if <code>length==-1</code> then
*        the text must be zero-terminated.
*
* @param paraLevel specifies the default level for the text;
*        it is typically 0 (LTR) or 1 (RTL).
*        If the function shall determine the paragraph level from the text,
*        then <code>paraLevel</code> can be set to
*        either <code>#UBIDI_DEFAULT_LTR</code>
*        or <code>#UBIDI_DEFAULT_RTL</code>; if the text contains multiple
*        paragraphs, the paragraph level shall be determined separately for
*        each paragraph; if a paragraph does not include any strongly typed
*        character, then the desired default is used (0 for LTR or 1 for RTL).
*        Any other value between 0 and <code>#UBIDI_MAX_EXPLICIT_LEVEL</code>
*        is also valid, with odd levels indicating RTL.
*
* @param embeddingLevels (in) may be used to preset the embedding and override levels,
*        ignoring characters like LRE and PDF in the text.
*        A level overrides the directional property of its corresponding
*        (same index) character if the level has the
*        <code>#UBIDI_LEVEL_OVERRIDE</code> bit set.<br><br>
*        Aside from that bit, it must be
*        <code>paraLevel<=embeddingLevels[]<=UBIDI_MAX_EXPLICIT_LEVEL</code>,
*        except that level 0 is always allowed.
*        Level 0 for a paragraph separator prevents reordering of paragraphs;
*        this only works reliably if <code>#UBIDI_LEVEL_OVERRIDE</code>
*        is also set for paragraph separators.
*        Level 0 for other characters is treated as a wildcard
*        and is lifted up to the resolved level of the surrounding paragraph.<br><br>
*        <strong>Caution: </strong>A copy of this pointer, not of the levels,
*        will be stored in the <code>UBiDi</code> object;
*        the <code>embeddingLevels</code> array must not be
*        deallocated before the <code>UBiDi</code> structure is destroyed or reused,
*        and the <code>embeddingLevels</code>
*        should not be modified to avoid unexpected results on subsequent Bidi operations.
*        However, the <code>ubidi_setPara()</code> and
*        <code>ubidi_setLine()</code> functions may modify some or all of the levels.<br><br>
*        After the <code>UBiDi</code> object is reused or destroyed, the caller
*        must take care of the deallocation of the <code>embeddingLevels</code> array.<br><br>
*        <strong>Note:</strong> the <code>embeddingLevels</code> array must be
*        at least <code>length</code> long.
*        This pointer can be <code>NULL</code> if this
*        value is not necessary.
*
* @param pErrorCode must be a valid pointer to an error code value.
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ubidi_setPara(UBiDi *pBiDi, const UChar *text, int32_t length,
             UBiDiLevel paraLevel, UBiDiLevel *embeddingLevels,
             UErrorCode *pErrorCode);

/**
* <code>ubidi_setLine()</code> sets a <code>UBiDi</code> to
* contain the reordering information, especially the resolved levels,
* for all the characters in a line of text. This line of text is
* specified by referring to a <code>UBiDi</code> object representing
* this information for a piece of text containing one or more paragraphs,
* and by specifying a range of indexes in this text.<p>
* In the new line object, the indexes will range from 0 to <code>limit-start-1</code>.<p>
*
* This is used after calling <code>ubidi_setPara()</code>
* for a piece of text, and after line-breaking on that text.
* It is not necessary if each paragraph is treated as a single line.<p>
*
* After line-breaking, rules (L1) and (L2) for the treatment of
* trailing WS and for reordering are performed on
* a <code>UBiDi</code> object that represents a line.<p>
*
* <strong>Important: </strong><code>pLineBiDi</code> shares data with
* <code>pParaBiDi</code>.
* You must destroy or reuse <code>pLineBiDi</code> before <code>pParaBiDi</code>.
* In other words, you must destroy or reuse the <code>UBiDi</code> object for a line
* before the object for its parent paragraph.<p>
*
* The text pointer that was stored in <code>pParaBiDi</code> is also copied,
* and <code>start</code> is added to it so that it points to the beginning of the
* line for this object.
*
* @param pParaBiDi is the parent paragraph object. It must have been set
* by a successful call to ubidi_setPara.
*
* @param start is the line's first index into the text.
*
* @param limit is just behind the line's last index into the text
*        (its last index +1).<br>
*        It must be <code>0<=start<limit<=</code>containing paragraph limit.
*        If the specified line crosses a paragraph boundary, the function
*        will terminate with error code U_ILLEGAL_ARGUMENT_ERROR.
*
* @param pLineBiDi is the object that will now represent a line of the text.
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @see ubidi_setPara
* @see ubidi_getProcessedLength
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ubidi_setLine(const UBiDi *pParaBiDi,
             int32_t start, int32_t limit,
             UBiDi *pLineBiDi,
             UErrorCode *pErrorCode);

/**
* Get the directionality of the text.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @return a value of <code>UBIDI_LTR</code>, <code>UBIDI_RTL</code>
*         or <code>UBIDI_MIXED</code>
*         that indicates if the entire text
*         represented by this object is unidirectional,
*         and which direction, or if it is mixed-directional.
* Note -  The value <code>UBIDI_NEUTRAL</code> is never returned from this method.
*
* @see UBiDiDirection
* @stable ICU 2.0
*/
U_CAPI UBiDiDirection U_EXPORT2
ubidi_getDirection(const UBiDi *pBiDi);

/**
* Gets the base direction of the text provided according
* to the Unicode Bidirectional Algorithm. The base direction
* is derived from the first character in the string with bidirectional
* character type L, R, or AL. If the first such character has type L,
* <code>UBIDI_LTR</code> is returned. If the first such character has
* type R or AL, <code>UBIDI_RTL</code> is returned. If the string does
* not contain any character of these types, then
* <code>UBIDI_NEUTRAL</code> is returned.
*
* This is a lightweight function for use when only the base direction
* is needed and no further bidi processing of the text is needed.
*
* @param text is a pointer to the text whose base
*             direction is needed.
* Note: the text must be (at least) @c length long.
*
* @param length is the length of the text;
*               if <code>length==-1</code> then the text
*               must be zero-terminated.
*
* @return  <code>UBIDI_LTR</code>, <code>UBIDI_RTL</code>,
*          <code>UBIDI_NEUTRAL</code>
*
* @see UBiDiDirection
* @stable ICU 4.6
*/
U_CAPI UBiDiDirection U_EXPORT2
ubidi_getBaseDirection(const UChar *text,  int32_t length );

/**
* Get the pointer to the text.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @return The pointer to the text that the UBiDi object was created for.
*
* @see ubidi_setPara
* @see ubidi_setLine
* @stable ICU 2.0
*/
U_CAPI const UChar * U_EXPORT2
ubidi_getText(const UBiDi *pBiDi);

/**
* Get the length of the text.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @return The length of the text that the UBiDi object was created for.
* @stable ICU 2.0
*/
U_CAPI int32_t U_EXPORT2
ubidi_getLength(const UBiDi *pBiDi);

/**
* Get the paragraph level of the text.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @return The paragraph level. If there are multiple paragraphs, their
*         level may vary if the required paraLevel is UBIDI_DEFAULT_LTR or
*         UBIDI_DEFAULT_RTL.  In that case, the level of the first paragraph
*         is returned.
*
* @see UBiDiLevel
* @see ubidi_getParagraph
* @see ubidi_getParagraphByIndex
* @stable ICU 2.0
*/
U_CAPI UBiDiLevel U_EXPORT2
ubidi_getParaLevel(const UBiDi *pBiDi);

/**
* Get the number of paragraphs.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @return The number of paragraphs.
* @stable ICU 3.4
*/
U_CAPI int32_t U_EXPORT2
ubidi_countParagraphs(UBiDi *pBiDi);

/**
* Get a paragraph, given a position within the text.
* This function returns information about a paragraph.<br>
* Note: if the paragraph index is known, it is more efficient to
* retrieve the paragraph information using ubidi_getParagraphByIndex().<p>
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @param charIndex is the index of a character within the text, in the
*        range <code>[0..ubidi_getProcessedLength(pBiDi)-1]</code>.
*
* @param pParaStart will receive the index of the first character of the
*        paragraph in the text.
*        This pointer can be <code>NULL</code> if this
*        value is not necessary.
*
* @param pParaLimit will receive the limit of the paragraph.
*        The l-value that you point to here may be the
*        same expression (variable) as the one for
*        <code>charIndex</code>.
*        This pointer can be <code>NULL</code> if this
*        value is not necessary.
*
* @param pParaLevel will receive the level of the paragraph.
*        This pointer can be <code>NULL</code> if this
*        value is not necessary.
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @return The index of the paragraph containing the specified position.
*
* @see ubidi_getProcessedLength
* @stable ICU 3.4
*/
U_CAPI int32_t U_EXPORT2
ubidi_getParagraph(const UBiDi *pBiDi, int32_t charIndex, int32_t *pParaStart,
                  int32_t *pParaLimit, UBiDiLevel *pParaLevel,
                  UErrorCode *pErrorCode);

/**
* Get a paragraph, given the index of this paragraph.
*
* This function returns information about a paragraph.<p>
*
* @param pBiDi is the paragraph <code>UBiDi</code> object.
*
* @param paraIndex is the number of the paragraph, in the
*        range <code>[0..ubidi_countParagraphs(pBiDi)-1]</code>.
*
* @param pParaStart will receive the index of the first character of the
*        paragraph in the text.
*        This pointer can be <code>NULL</code> if this
*        value is not necessary.
*
* @param pParaLimit will receive the limit of the paragraph.
*        This pointer can be <code>NULL</code> if this
*        value is not necessary.
*
* @param pParaLevel will receive the level of the paragraph.
*        This pointer can be <code>NULL</code> if this
*        value is not necessary.
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @stable ICU 3.4
*/
U_CAPI void U_EXPORT2
ubidi_getParagraphByIndex(const UBiDi *pBiDi, int32_t paraIndex,
                         int32_t *pParaStart, int32_t *pParaLimit,
                         UBiDiLevel *pParaLevel, UErrorCode *pErrorCode);

/**
* Get the level for one character.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @param charIndex the index of a character. It must be in the range
*         [0..ubidi_getProcessedLength(pBiDi)].
*
* @return The level for the character at charIndex (0 if charIndex is not
*         in the valid range).
*
* @see UBiDiLevel
* @see ubidi_getProcessedLength
* @stable ICU 2.0
*/
U_CAPI UBiDiLevel U_EXPORT2
ubidi_getLevelAt(const UBiDi *pBiDi, int32_t charIndex);

/**
* Get an array of levels for each character.<p>
*
* Note that this function may allocate memory under some
* circumstances, unlike <code>ubidi_getLevelAt()</code>.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object, whose
*        text length must be strictly positive.
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @return The levels array for the text,
*         or <code>NULL</code> if an error occurs.
*
* @see UBiDiLevel
* @see ubidi_getProcessedLength
* @stable ICU 2.0
*/
U_CAPI const UBiDiLevel * U_EXPORT2
ubidi_getLevels(UBiDi *pBiDi, UErrorCode *pErrorCode);

/**
* Get a logical run.
* This function returns information about a run and is used
* to retrieve runs in logical order.<p>
* This is especially useful for line-breaking on a paragraph.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @param logicalPosition is a logical position within the source text.
*
* @param pLogicalLimit will receive the limit of the corresponding run.
*        The l-value that you point to here may be the
*        same expression (variable) as the one for
*        <code>logicalPosition</code>.
*        This pointer can be <code>NULL</code> if this
*        value is not necessary.
*
* @param pLevel will receive the level of the corresponding run.
*        This pointer can be <code>NULL</code> if this
*        value is not necessary.
*
* @see ubidi_getProcessedLength
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ubidi_getLogicalRun(const UBiDi *pBiDi, int32_t logicalPosition,
                   int32_t *pLogicalLimit, UBiDiLevel *pLevel);

/**
* Get the number of runs.
* This function may invoke the actual reordering on the
* <code>UBiDi</code> object, after <code>ubidi_setPara()</code>
* may have resolved only the levels of the text. Therefore,
* <code>ubidi_countRuns()</code> may have to allocate memory,
* and may fail doing so.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @return The number of runs.
* @stable ICU 2.0
*/
U_CAPI int32_t U_EXPORT2
ubidi_countRuns(UBiDi *pBiDi, UErrorCode *pErrorCode);

/**
* Get one run's logical start, length, and directionality,
* which can be 0 for LTR or 1 for RTL.
* In an RTL run, the character at the logical start is
* visually on the right of the displayed run.
* The length is the number of characters in the run.<p>
* <code>ubidi_countRuns()</code> should be called
* before the runs are retrieved.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @param runIndex is the number of the run in visual order, in the
*        range <code>[0..ubidi_countRuns(pBiDi)-1]</code>.
*
* @param pLogicalStart is the first logical character index in the text.
*        The pointer may be <code>NULL</code> if this index is not needed.
*
* @param pLength is the number of characters (at least one) in the run.
*        The pointer may be <code>NULL</code> if this is not needed.
*
* @return the directionality of the run,
*         <code>UBIDI_LTR==0</code> or <code>UBIDI_RTL==1</code>,
*         never <code>UBIDI_MIXED</code>,
*         never <code>UBIDI_NEUTRAL</code>.
*
* @see ubidi_countRuns
*
* Example:
* <pre>
* \code
* int32_t i, count=ubidi_countRuns(pBiDi),
*         logicalStart, visualIndex=0, length;
* for(i=0; i<count; ++i) {
*    if(UBIDI_LTR==ubidi_getVisualRun(pBiDi, i, &logicalStart, &length)) {
*         do { // LTR
*             show_char(text[logicalStart++], visualIndex++);
*         } while(--length>0);
*     } else {
*         logicalStart+=length;  // logicalLimit
*         do { // RTL
*             show_char(text[--logicalStart], visualIndex++);
*         } while(--length>0);
*     }
* }
*\endcode
* </pre>
*
* Note that in right-to-left runs, code like this places
* second surrogates before first ones (which is generally a bad idea)
* and combining characters before base characters.
* <p>
* Use of <code>ubidi_writeReordered()</code>, optionally with the
* <code>#UBIDI_KEEP_BASE_COMBINING</code> option, can be considered in order
* to avoid these issues.
* @stable ICU 2.0
*/
U_CAPI UBiDiDirection U_EXPORT2
ubidi_getVisualRun(UBiDi *pBiDi, int32_t runIndex,
                  int32_t *pLogicalStart, int32_t *pLength);

/**
* Get the visual position from a logical text position.
* If such a mapping is used many times on the same
* <code>UBiDi</code> object, then calling
* <code>ubidi_getLogicalMap()</code> is more efficient.<p>
*
* The value returned may be <code>#UBIDI_MAP_NOWHERE</code> if there is no
* visual position because the corresponding text character is a Bidi control
* removed from output by the option <code>#UBIDI_OPTION_REMOVE_CONTROLS</code>.
* <p>
* When the visual output is altered by using options of
* <code>ubidi_writeReordered()</code> such as <code>UBIDI_INSERT_LRM_FOR_NUMERIC</code>,
* <code>UBIDI_KEEP_BASE_COMBINING</code>, <code>UBIDI_OUTPUT_REVERSE</code>,
* <code>UBIDI_REMOVE_BIDI_CONTROLS</code>, the visual position returned may not
* be correct. It is advised to use, when possible, reordering options
* such as <code>UBIDI_OPTION_INSERT_MARKS</code> and <code>UBIDI_OPTION_REMOVE_CONTROLS</code>.
* <p>
* Note that in right-to-left runs, this mapping places
* second surrogates before first ones (which is generally a bad idea)
* and combining characters before base characters.
* Use of <code>ubidi_writeReordered()</code>, optionally with the
* <code>#UBIDI_KEEP_BASE_COMBINING</code> option can be considered instead
* of using the mapping, in order to avoid these issues.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @param logicalIndex is the index of a character in the text.
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @return The visual position of this character.
*
* @see ubidi_getLogicalMap
* @see ubidi_getLogicalIndex
* @see ubidi_getProcessedLength
* @stable ICU 2.0
*/
U_CAPI int32_t U_EXPORT2
ubidi_getVisualIndex(UBiDi *pBiDi, int32_t logicalIndex, UErrorCode *pErrorCode);

/**
* Get the logical text position from a visual position.
* If such a mapping is used many times on the same
* <code>UBiDi</code> object, then calling
* <code>ubidi_getVisualMap()</code> is more efficient.<p>
*
* The value returned may be <code>#UBIDI_MAP_NOWHERE</code> if there is no
* logical position because the corresponding text character is a Bidi mark
* inserted in the output by option <code>#UBIDI_OPTION_INSERT_MARKS</code>.
* <p>
* This is the inverse function to <code>ubidi_getVisualIndex()</code>.
* <p>
* When the visual output is altered by using options of
* <code>ubidi_writeReordered()</code> such as <code>UBIDI_INSERT_LRM_FOR_NUMERIC</code>,
* <code>UBIDI_KEEP_BASE_COMBINING</code>, <code>UBIDI_OUTPUT_REVERSE</code>,
* <code>UBIDI_REMOVE_BIDI_CONTROLS</code>, the logical position returned may not
* be correct. It is advised to use, when possible, reordering options
* such as <code>UBIDI_OPTION_INSERT_MARKS</code> and <code>UBIDI_OPTION_REMOVE_CONTROLS</code>.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @param visualIndex is the visual position of a character.
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @return The index of this character in the text.
*
* @see ubidi_getVisualMap
* @see ubidi_getVisualIndex
* @see ubidi_getResultLength
* @stable ICU 2.0
*/
U_CAPI int32_t U_EXPORT2
ubidi_getLogicalIndex(UBiDi *pBiDi, int32_t visualIndex, UErrorCode *pErrorCode);

/**
* Get a logical-to-visual index map (array) for the characters in the UBiDi
* (paragraph or line) object.
* <p>
* Some values in the map may be <code>#UBIDI_MAP_NOWHERE</code> if the
* corresponding text characters are Bidi controls removed from the visual
* output by the option <code>#UBIDI_OPTION_REMOVE_CONTROLS</code>.
* <p>
* When the visual output is altered by using options of
* <code>ubidi_writeReordered()</code> such as <code>UBIDI_INSERT_LRM_FOR_NUMERIC</code>,
* <code>UBIDI_KEEP_BASE_COMBINING</code>, <code>UBIDI_OUTPUT_REVERSE</code>,
* <code>UBIDI_REMOVE_BIDI_CONTROLS</code>, the visual positions returned may not
* be correct. It is advised to use, when possible, reordering options
* such as <code>UBIDI_OPTION_INSERT_MARKS</code> and <code>UBIDI_OPTION_REMOVE_CONTROLS</code>.
* <p>
* Note that in right-to-left runs, this mapping places
* second surrogates before first ones (which is generally a bad idea)
* and combining characters before base characters.
* Use of <code>ubidi_writeReordered()</code>, optionally with the
* <code>#UBIDI_KEEP_BASE_COMBINING</code> option can be considered instead
* of using the mapping, in order to avoid these issues.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @param indexMap is a pointer to an array of <code>ubidi_getProcessedLength()</code>
*        indexes which will reflect the reordering of the characters.
*        If option <code>#UBIDI_OPTION_INSERT_MARKS</code> is set, the number
*        of elements allocated in <code>indexMap</code> must be no less than
*        <code>ubidi_getResultLength()</code>.
*        The array does not need to be initialized.<br><br>
*        The index map will result in <code>indexMap[logicalIndex]==visualIndex</code>.
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @see ubidi_getVisualMap
* @see ubidi_getVisualIndex
* @see ubidi_getProcessedLength
* @see ubidi_getResultLength
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ubidi_getLogicalMap(UBiDi *pBiDi, int32_t *indexMap, UErrorCode *pErrorCode);

/**
* Get a visual-to-logical index map (array) for the characters in the UBiDi
* (paragraph or line) object.
* <p>
* Some values in the map may be <code>#UBIDI_MAP_NOWHERE</code> if the
* corresponding text characters are Bidi marks inserted in the visual output
* by the option <code>#UBIDI_OPTION_INSERT_MARKS</code>.
* <p>
* When the visual output is altered by using options of
* <code>ubidi_writeReordered()</code> such as <code>UBIDI_INSERT_LRM_FOR_NUMERIC</code>,
* <code>UBIDI_KEEP_BASE_COMBINING</code>, <code>UBIDI_OUTPUT_REVERSE</code>,
* <code>UBIDI_REMOVE_BIDI_CONTROLS</code>, the logical positions returned may not
* be correct. It is advised to use, when possible, reordering options
* such as <code>UBIDI_OPTION_INSERT_MARKS</code> and <code>UBIDI_OPTION_REMOVE_CONTROLS</code>.
*
* @param pBiDi is the paragraph or line <code>UBiDi</code> object.
*
* @param indexMap is a pointer to an array of <code>ubidi_getResultLength()</code>
*        indexes which will reflect the reordering of the characters.
*        If option <code>#UBIDI_OPTION_REMOVE_CONTROLS</code> is set, the number
*        of elements allocated in <code>indexMap</code> must be no less than
*        <code>ubidi_getProcessedLength()</code>.
*        The array does not need to be initialized.<br><br>
*        The index map will result in <code>indexMap[visualIndex]==logicalIndex</code>.
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @see ubidi_getLogicalMap
* @see ubidi_getLogicalIndex
* @see ubidi_getProcessedLength
* @see ubidi_getResultLength
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ubidi_getVisualMap(UBiDi *pBiDi, int32_t *indexMap, UErrorCode *pErrorCode);

/**
* This is a convenience function that does not use a UBiDi object.
* It is intended to be used for when an application has determined the levels
* of objects (character sequences) and just needs to have them reordered (L2).
* This is equivalent to using <code>ubidi_getLogicalMap()</code> on a
* <code>UBiDi</code> object.
*
* @param levels is an array with <code>length</code> levels that have been determined by
*        the application.
*
* @param length is the number of levels in the array, or, semantically,
*        the number of objects to be reordered.
*        It must be <code>length>0</code>.
*
* @param indexMap is a pointer to an array of <code>length</code>
*        indexes which will reflect the reordering of the characters.
*        The array does not need to be initialized.<p>
*        The index map will result in <code>indexMap[logicalIndex]==visualIndex</code>.
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ubidi_reorderLogical(const UBiDiLevel *levels, int32_t length, int32_t *indexMap);

/**
* This is a convenience function that does not use a UBiDi object.
* It is intended to be used for when an application has determined the levels
* of objects (character sequences) and just needs to have them reordered (L2).
* This is equivalent to using <code>ubidi_getVisualMap()</code> on a
* <code>UBiDi</code> object.
*
* @param levels is an array with <code>length</code> levels that have been determined by
*        the application.
*
* @param length is the number of levels in the array, or, semantically,
*        the number of objects to be reordered.
*        It must be <code>length>0</code>.
*
* @param indexMap is a pointer to an array of <code>length</code>
*        indexes which will reflect the reordering of the characters.
*        The array does not need to be initialized.<p>
*        The index map will result in <code>indexMap[visualIndex]==logicalIndex</code>.
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ubidi_reorderVisual(const UBiDiLevel *levels, int32_t length, int32_t *indexMap);

/**
* Invert an index map.
* The index mapping of the first map is inverted and written to
* the second one.
*
* @param srcMap is an array with <code>length</code> elements
*        which defines the original mapping from a source array containing
*        <code>length</code> elements to a destination array.
*        Some elements of the source array may have no mapping in the
*        destination array. In that case, their value will be
*        the special value <code>UBIDI_MAP_NOWHERE</code>.
*        All elements must be >=0 or equal to <code>UBIDI_MAP_NOWHERE</code>.
*        Some elements may have a value >= <code>length</code>, if the
*        destination array has more elements than the source array.
*        There must be no duplicate indexes (two or more elements with the
*        same value except <code>UBIDI_MAP_NOWHERE</code>).
*
* @param destMap is an array with a number of elements equal to 1 + the highest
*        value in <code>srcMap</code>.
*        <code>destMap</code> will be filled with the inverse mapping.
*        If element with index i in <code>srcMap</code> has a value k different
*        from <code>UBIDI_MAP_NOWHERE</code>, this means that element i of
*        the source array maps to element k in the destination array.
*        The inverse map will have value i in its k-th element.
*        For all elements of the destination array which do not map to
*        an element in the source array, the corresponding element in the
*        inverse map will have a value equal to <code>UBIDI_MAP_NOWHERE</code>.
*
* @param length is the length of each array.
* @see UBIDI_MAP_NOWHERE
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ubidi_invertMap(const int32_t *srcMap, int32_t *destMap, int32_t length);

/** option flags for ubidi_writeReordered() */

/**
* option bit for ubidi_writeReordered():
* keep combining characters after their base characters in RTL runs
*
* @see ubidi_writeReordered
* @stable ICU 2.0
*/
#define UBIDI_KEEP_BASE_COMBINING       1

/**
* option bit for ubidi_writeReordered():
* replace characters with the "mirrored" property in RTL runs
* by their mirror-image mappings
*
* @see ubidi_writeReordered
* @stable ICU 2.0
*/
#define UBIDI_DO_MIRRORING              2

/**
* option bit for ubidi_writeReordered():
* surround the run with LRMs if necessary;
* this is part of the approximate "inverse Bidi" algorithm
*
* <p>This option does not imply corresponding adjustment of the index
* mappings.</p>
*
* @see ubidi_setInverse
* @see ubidi_writeReordered
* @stable ICU 2.0
*/
#define UBIDI_INSERT_LRM_FOR_NUMERIC    4

/**
* option bit for ubidi_writeReordered():
* remove Bidi control characters
* (this does not affect #UBIDI_INSERT_LRM_FOR_NUMERIC)
*
* <p>This option does not imply corresponding adjustment of the index
* mappings.</p>
*
* @see ubidi_writeReordered
* @stable ICU 2.0
*/
#define UBIDI_REMOVE_BIDI_CONTROLS      8

/**
* option bit for ubidi_writeReordered():
* write the output in reverse order
*
* <p>This has the same effect as calling <code>ubidi_writeReordered()</code>
* first without this option, and then calling
* <code>ubidi_writeReverse()</code> without mirroring.
* Doing this in the same step is faster and avoids a temporary buffer.
* An example for using this option is output to a character terminal that
* is designed for RTL scripts and stores text in reverse order.</p>
*
* @see ubidi_writeReordered
* @stable ICU 2.0
*/
#define UBIDI_OUTPUT_REVERSE            16

/**
* Get the length of the source text processed by the last call to
* <code>ubidi_setPara()</code>. This length may be different from the length
* of the source text if option <code>#UBIDI_OPTION_STREAMING</code>
* has been set.
* <br>
* Note that whenever the length of the text affects the execution or the
* result of a function, it is the processed length which must be considered,
* except for <code>ubidi_setPara</code> (which receives unprocessed source
* text) and <code>ubidi_getLength</code> (which returns the original length
* of the source text).<br>
* In particular, the processed length is the one to consider in the following
* cases:
* <ul>
* <li>maximum value of the <code>limit</code> argument of
* <code>ubidi_setLine</code></li>
* <li>maximum value of the <code>charIndex</code> argument of
* <code>ubidi_getParagraph</code></li>
* <li>maximum value of the <code>charIndex</code> argument of
* <code>ubidi_getLevelAt</code></li>
* <li>number of elements in the array returned by <code>ubidi_getLevels</code></li>
* <li>maximum value of the <code>logicalStart</code> argument of
* <code>ubidi_getLogicalRun</code></li>
* <li>maximum value of the <code>logicalIndex</code> argument of
* <code>ubidi_getVisualIndex</code></li>
* <li>number of elements filled in the <code>*indexMap</code> argument of
* <code>ubidi_getLogicalMap</code></li>
* <li>length of text processed by <code>ubidi_writeReordered</code></li>
* </ul>
*
* @param pBiDi is the paragraph <code>UBiDi</code> object.
*
* @return The length of the part of the source text processed by
*         the last call to <code>ubidi_setPara</code>.
* @see ubidi_setPara
* @see UBIDI_OPTION_STREAMING
* @stable ICU 3.6
*/
U_CAPI int32_t U_EXPORT2
ubidi_getProcessedLength(const UBiDi *pBiDi);

/**
* Get the length of the reordered text resulting from the last call to
* <code>ubidi_setPara()</code>. This length may be different from the length
* of the source text if option <code>#UBIDI_OPTION_INSERT_MARKS</code>
* or option <code>#UBIDI_OPTION_REMOVE_CONTROLS</code> has been set.
* <br>
* This resulting length is the one to consider in the following cases:
* <ul>
* <li>maximum value of the <code>visualIndex</code> argument of
* <code>ubidi_getLogicalIndex</code></li>
* <li>number of elements of the <code>*indexMap</code> argument of
* <code>ubidi_getVisualMap</code></li>
* </ul>
* Note that this length stays identical to the source text length if
* Bidi marks are inserted or removed using option bits of
* <code>ubidi_writeReordered</code>, or if option
* <code>#UBIDI_REORDER_INVERSE_NUMBERS_AS_L</code> has been set.
*
* @param pBiDi is the paragraph <code>UBiDi</code> object.
*
* @return The length of the reordered text resulting from
*         the last call to <code>ubidi_setPara</code>.
* @see ubidi_setPara
* @see UBIDI_OPTION_INSERT_MARKS
* @see UBIDI_OPTION_REMOVE_CONTROLS
* @stable ICU 3.6
*/
U_CAPI int32_t U_EXPORT2
ubidi_getResultLength(const UBiDi *pBiDi);

U_CDECL_BEGIN

#ifndef U_HIDE_DEPRECATED_API
/**
* Value returned by <code>UBiDiClassCallback</code> callbacks when
* there is no need to override the standard Bidi class for a given code point.
*
* This constant is deprecated; use u_getIntPropertyMaxValue(UCHAR_BIDI_CLASS)+1 instead.
*
* @see UBiDiClassCallback
* @deprecated ICU 58 The numeric value may change over time, see ICU ticket #12420.
*/
#define U_BIDI_CLASS_DEFAULT  U_CHAR_DIRECTION_COUNT
#endif  // U_HIDE_DEPRECATED_API

/**
* Callback type declaration for overriding default Bidi class values with
* custom ones.
* <p>Usually, the function pointer will be propagated to a <code>UBiDi</code>
* object by calling the <code>ubidi_setClassCallback()</code> function;
* then the callback will be invoked by the UBA implementation any time the
* class of a character is to be determined.</p>
*
* @param context is a pointer to the callback private data.
*
* @param c       is the code point to get a Bidi class for.
*
* @return The directional property / Bidi class for the given code point
*         <code>c</code> if the default class has been overridden, or
*         <code>u_getIntPropertyMaxValue(UCHAR_BIDI_CLASS)+1</code>
*         if the standard Bidi class value for <code>c</code> is to be used.
* @see ubidi_setClassCallback
* @see ubidi_getClassCallback
* @stable ICU 3.6
*/
typedef UCharDirection U_CALLCONV
UBiDiClassCallback(const void *context, UChar32 c);

U_CDECL_END

/**
* Retrieve the Bidi class for a given code point.
* <p>If a <code>#UBiDiClassCallback</code> callback is defined and returns a
* value other than <code>u_getIntPropertyMaxValue(UCHAR_BIDI_CLASS)+1</code>,
* that value is used; otherwise the default class determination mechanism is invoked.</p>
*
* @param pBiDi is the paragraph <code>UBiDi</code> object.
*
* @param c     is the code point whose Bidi class must be retrieved.
*
* @return The Bidi class for character <code>c</code> based
*         on the given <code>pBiDi</code> instance.
* @see UBiDiClassCallback
* @stable ICU 3.6
*/
U_CAPI UCharDirection U_EXPORT2
ubidi_getCustomizedClass(UBiDi *pBiDi, UChar32 c);

/**
* Set the callback function and callback data used by the UBA
* implementation for Bidi class determination.
* <p>This may be useful for assigning Bidi classes to PUA characters, or
* for special application needs. For instance, an application may want to
* handle all spaces like L or R characters (according to the base direction)
* when creating the visual ordering of logical lines which are part of a report
* organized in columns: there should not be interaction between adjacent
* cells.<p>
*
* @param pBiDi is the paragraph <code>UBiDi</code> object.
*
* @param newFn is the new callback function pointer.
*
* @param newContext is the new callback context pointer. This can be NULL.
*
* @param oldFn fillin: Returns the old callback function pointer. This can be
*                      NULL.
*
* @param oldContext fillin: Returns the old callback's context. This can be
*                           NULL.
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @see ubidi_getClassCallback
* @stable ICU 3.6
*/
U_CAPI void U_EXPORT2
ubidi_setClassCallback(UBiDi *pBiDi, UBiDiClassCallback *newFn,
                      const void *newContext, UBiDiClassCallback **oldFn,
                      const void **oldContext, UErrorCode *pErrorCode);

/**
* Get the current callback function used for Bidi class determination.
*
* @param pBiDi is the paragraph <code>UBiDi</code> object.
*
* @param fn fillin: Returns the callback function pointer.
*
* @param context fillin: Returns the callback's private context.
*
* @see ubidi_setClassCallback
* @stable ICU 3.6
*/
U_CAPI void U_EXPORT2
ubidi_getClassCallback(UBiDi *pBiDi, UBiDiClassCallback **fn, const void **context);

/**
* Take a <code>UBiDi</code> object containing the reordering
* information for a piece of text (one or more paragraphs) set by
* <code>ubidi_setPara()</code> or for a line of text set by
* <code>ubidi_setLine()</code> and write a reordered string to the
* destination buffer.
*
* This function preserves the integrity of characters with multiple
* code units and (optionally) combining characters.
* Characters in RTL runs can be replaced by mirror-image characters
* in the destination buffer. Note that "real" mirroring has
* to be done in a rendering engine by glyph selection
* and that for many "mirrored" characters there are no
* Unicode characters as mirror-image equivalents.
* There are also options to insert or remove Bidi control
* characters; see the description of the <code>destSize</code>
* and <code>options</code> parameters and of the option bit flags.
*
* @param pBiDi A pointer to a <code>UBiDi</code> object that
*              is set by <code>ubidi_setPara()</code> or
*              <code>ubidi_setLine()</code> and contains the reordering
*              information for the text that it was defined for,
*              as well as a pointer to that text.<br><br>
*              The text was aliased (only the pointer was stored
*              without copying the contents) and must not have been modified
*              since the <code>ubidi_setPara()</code> call.
*
* @param dest A pointer to where the reordered text is to be copied.
*             The source text and <code>dest[destSize]</code>
*             must not overlap.
*
* @param destSize The size of the <code>dest</code> buffer,
*                 in number of UChars.
*                 If the <code>UBIDI_INSERT_LRM_FOR_NUMERIC</code>
*                 option is set, then the destination length could be
*                 as large as
*                 <code>ubidi_getLength(pBiDi)+2*ubidi_countRuns(pBiDi)</code>.
*                 If the <code>UBIDI_REMOVE_BIDI_CONTROLS</code> option
*                 is set, then the destination length may be less than
*                 <code>ubidi_getLength(pBiDi)</code>.
*                 If none of these options is set, then the destination length
*                 will be exactly <code>ubidi_getProcessedLength(pBiDi)</code>.
*
* @param options A bit set of options for the reordering that control
*                how the reordered text is written.
*                The options include mirroring the characters on a code
*                point basis and inserting LRM characters, which is used
*                especially for transforming visually stored text
*                to logically stored text (although this is still an
*                imperfect implementation of an "inverse Bidi" algorithm
*                because it uses the "forward Bidi" algorithm at its core).
*                The available options are:
*                <code>#UBIDI_DO_MIRRORING</code>,
*                <code>#UBIDI_INSERT_LRM_FOR_NUMERIC</code>,
*                <code>#UBIDI_KEEP_BASE_COMBINING</code>,
*                <code>#UBIDI_OUTPUT_REVERSE</code>,
*                <code>#UBIDI_REMOVE_BIDI_CONTROLS</code>
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @return The length of the output string.
*
* @see ubidi_getProcessedLength
* @stable ICU 2.0
*/
U_CAPI int32_t U_EXPORT2
ubidi_writeReordered(UBiDi *pBiDi,
                    UChar *dest, int32_t destSize,
                    uint16_t options,
                    UErrorCode *pErrorCode);

/**
* Reverse a Right-To-Left run of Unicode text.
*
* This function preserves the integrity of characters with multiple
* code units and (optionally) combining characters.
* Characters can be replaced by mirror-image characters
* in the destination buffer. Note that "real" mirroring has
* to be done in a rendering engine by glyph selection
* and that for many "mirrored" characters there are no
* Unicode characters as mirror-image equivalents.
* There are also options to insert or remove Bidi control
* characters.
*
* This function is the implementation for reversing RTL runs as part
* of <code>ubidi_writeReordered()</code>. For detailed descriptions
* of the parameters, see there.
* Since no Bidi controls are inserted here, the output string length
* will never exceed <code>srcLength</code>.
*
* @see ubidi_writeReordered
*
* @param src A pointer to the RTL run text.
*
* @param srcLength The length of the RTL run.
*
* @param dest A pointer to where the reordered text is to be copied.
*             <code>src[srcLength]</code> and <code>dest[destSize]</code>
*             must not overlap.
*
* @param destSize The size of the <code>dest</code> buffer,
*                 in number of UChars.
*                 If the <code>UBIDI_REMOVE_BIDI_CONTROLS</code> option
*                 is set, then the destination length may be less than
*                 <code>srcLength</code>.
*                 If this option is not set, then the destination length
*                 will be exactly <code>srcLength</code>.
*
* @param options A bit set of options for the reordering that control
*                how the reordered text is written.
*                See the <code>options</code> parameter in <code>ubidi_writeReordered()</code>.
*
* @param pErrorCode must be a valid pointer to an error code value.
*
* @return The length of the output string.
* @stable ICU 2.0
*/
U_CAPI int32_t U_EXPORT2
ubidi_writeReverse(const UChar *src, int32_t srcLength,
                  UChar *dest, int32_t destSize,
                  uint16_t options,
                  UErrorCode *pErrorCode);

/*#define BIDI_SAMPLE_CODE*/
/*@}*/

#endif